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/*
* Copyright (c) 1999 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of KTH nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY KTH AND ITS CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KTH OR ITS CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
#include "krb5_locl.h"
RCSID("$Id: n-fold.c,v 1.6 1999/08/27 09:03:41 joda Exp $");
static void
rr13(unsigned char *buf, size_t len)
{
unsigned char *tmp;
int bytes = (len + 7) / 8;
int i;
if(len == 0)
return;
{
const int bits = 13 % len;
const int lbit = len % 8;
tmp = malloc(bytes);
memcpy(tmp, buf, bytes);
if(lbit) {
/* pad final byte with inital bits */
tmp[bytes - 1] &= 0xff << (8 - lbit);
for(i = lbit; i < 8; i += len)
tmp[bytes - 1] |= buf[0] >> i;
}
for(i = 0; i < bytes; i++) {
int bb;
int b1, s1, b2, s2;
/* calculate first bit position of this byte */
bb = 8 * i - bits;
while(bb < 0)
bb += len;
/* byte offset and shift count */
b1 = bb / 8;
s1 = bb % 8;
if(bb + 8 > bytes * 8)
/* watch for wraparound */
s2 = (len + 8 - s1) % 8;
else
s2 = 8 - s1;
b2 = (b1 + 1) % bytes;
buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
}
free(tmp);
}
}
/* Add `b' to `a', both beeing one's complement numbers. */
static void
add1(unsigned char *a, unsigned char *b, size_t len)
{
int i;
int carry = 0;
for(i = len - 1; i >= 0; i--){
int x = a[i] + b[i] + carry;
carry = x > 0xff;
a[i] = x & 0xff;
}
for(i = len - 1; carry && i >= 0; i--){
int x = a[i] + carry;
carry = x > 0xff;
a[i] = x & 0xff;
}
}
void
_krb5_n_fold(const void *str, size_t len, void *key, size_t size)
{
/* if len < size we need at most N * len bytes, ie < 2 * size;
if len > size we need at most 2 * len */
size_t maxlen = 2 * max(size, len);
size_t l = 0;
unsigned char *tmp = malloc(maxlen);
unsigned char *buf = malloc(len);
memcpy(buf, str, len);
memset(key, 0, size);
do {
memcpy(tmp + l, buf, len);
l += len;
rr13(buf, len * 8);
while(l >= size) {
add1(key, tmp, size);
l -= size;
if(l == 0)
break;
memmove(tmp, tmp + size, l);
}
} while(l != 0);
memset(buf, 0, len);
free(buf);
memset(tmp, 0, maxlen);
free(tmp);
}
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